Conventional resistors typically include doped polycrystalline silicon (polysilicon) resistive elements patterned to form a desired geometry. Contacts are formed at opposite ends of each doped polysilicon resistive element, such as from patterned silicide patches. The contacts define a conductive path to the doped polysilicon resistive elements and facilitate integration of the resistor with other semiconductor structures.
Resistors formed from doped polysilicon resistive elements typically suffer from high variability in resistance. For example, the resistance of resistors formed from doped polysilicon resistive elements may vary because of non-uniform hydrogen penetration into the polysilicon. Further, the resistance may vary due to the non-uniformity of doping processes. The resistance variability of resistors is a key concern in analog and digital circuit design.
Conventionally-formed polysilicon resistors may take up a relatively large area of a semiconductor substrate of an integrated circuit. As the critical dimensions of integrated circuits continue to shrink, the area of a semiconductor substrate or “footprint” available for forming resistor structures is reduced. Nevertheless, circuit designs may require a high resistance resistor or low resistance resistor formed in a relatively small footprint of semiconductor substrate.
Accordingly, it is desirable to provide integrated circuits and methods for fabricating integrated circuits having resistor structures with improved uniformity of resistance. Also, it is desirable to provide integrated circuits and methods for fabricating integrated circuits with resistor structures formed from a material other than polysilicon, i.e., gate metal. Further, it is desirable to provide integrated circuits and methods for fabricating integrated circuits with resistor structures having effective lengths or widths greater than the respective length or width of the provided semiconductor substrate footprint. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.